/*
 * Copyright (c) 2015-2018 Nexenta Systems, inc.
 *
 * This file is part of EdgeFS Project
 * (see https://github.com/Nexenta/edgefs).
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

/* Notice extracted from xxHash homepage :

xxHash is an extremely fast Hash algorithm, running at RAM speed limits.
It also successfully passes all tests from the SMHasher suite.

Comparison (single thread, Windows Seven 32 bits, using SMHasher on a Core 2 Duo @3GHz)

Name            Speed       Q.Score   Author
xxHash          5.4 GB/s     10
CrapWow         3.2 GB/s      2       Andrew
MumurHash 3a    2.7 GB/s     10       Austin Appleby
SpookyHash      2.0 GB/s     10       Bob Jenkins
SBox            1.4 GB/s      9       Bret Mulvey
Lookup3         1.2 GB/s      9       Bob Jenkins
SuperFastHash   1.2 GB/s      1       Paul Hsieh
CityHash64      1.05 GB/s    10       Pike & Alakuijala
FNV             0.55 GB/s     5       Fowler, Noll, Vo
CRC32           0.43 GB/s     9
MD5-32          0.33 GB/s    10       Ronald L. Rivest
SHA1-32         0.28 GB/s    10

Q.Score is a measure of quality of the hash function.
It depends on successfully passing SMHasher test set.
10 is a perfect score.
*/

#pragma once

#if defined (__cplusplus)
extern "C" {
#endif


/*****************************
   Includes
*****************************/
#include <stddef.h>   /* size_t */


/*****************************
   Type
*****************************/
typedef enum { XXH_OK=0, XXH_ERROR } XXH_errorcode;



/*****************************
   Simple Hash Functions
*****************************/

unsigned int       XXH32 (const void* input, size_t length, unsigned seed);
unsigned long long XXH64 (const void* input, size_t length, unsigned long long seed);
void 			   XXH128 (const void* input, size_t length, unsigned long long seed, void* out);
void 			   XXH256 (const void* input, size_t length, unsigned long long seed, void* out);

/*
XXH32() :
    Calculate the 32-bits hash of sequence "length" bytes stored at memory address "input".
    The memory between input & input+length must be valid (allocated and read-accessible).
    "seed" can be used to alter the result predictably.
    This function successfully passes all SMHasher tests.
    Speed on Core 2 Duo @ 3 GHz (single thread, SMHasher benchmark) : 5.4 GB/s
XXH64() :
    Calculate the 64-bits hash of sequence of length "len" stored at memory address "input".
XXH128():
    Calculate the 128-bits hash of sequence of length "len" stored at memory address "input".
    Output is stored in the 16 byte array "out"
XXH256():
    Calculate the 256-bits hash of sequence of length "len" stored at memory address "input".
    Output is stored in the 32 byte array "out"
*/



/*****************************
   Advanced Hash Functions
*****************************/
typedef struct { long long ll[ 6]; } XXH32_state_t;
typedef struct { long long ll[11]; } XXH64_state_t;
typedef struct { long long ll[28]; } XXH128_state_t;
typedef struct { long long ll[28]; } XXH256_state_t;

/*
These structures allow static allocation of XXH states.
States must then be initialized using XXHnn_reset() before first use.

If you prefer dynamic allocation, please refer to functions below.
*/

XXH32_state_t* XXH32_createState(void);
XXH_errorcode  XXH32_freeState(XXH32_state_t* statePtr);

XXH64_state_t* XXH64_createState(void);
XXH_errorcode  XXH64_freeState(XXH64_state_t* statePtr);

XXH128_state_t* XXH128_createState(void);
XXH_errorcode   XXH128_freeState(XXH128_state_t* statePtr);

XXH256_state_t* XXH256_createState(void);
XXH_errorcode   XXH256_freeState(XXH256_state_t* statePtr);

/*
These functions create and release memory for XXH state.
States must then be initialized using XXHnn_reset() before first use.
*/


XXH_errorcode XXH32_reset  (XXH32_state_t* statePtr, unsigned seed);
XXH_errorcode XXH32_update (XXH32_state_t* statePtr, const void* input, size_t length);
unsigned int  XXH32_digest (const XXH32_state_t* statePtr);

XXH_errorcode      XXH64_reset  (XXH64_state_t* statePtr, unsigned long long seed);
XXH_errorcode      XXH64_update (XXH64_state_t* statePtr, const void* input, size_t length);
unsigned long long XXH64_digest (const XXH64_state_t* statePtr);

XXH_errorcode      XXH128_reset  (XXH128_state_t* statePtr, unsigned long long seed);
XXH_errorcode      XXH128_update (XXH128_state_t* statePtr, const void* input, size_t length);
void               XXH128_digest (const XXH128_state_t* statePtr, void* out);

XXH_errorcode      XXH256_reset  (XXH256_state_t* statePtr, unsigned long long seed);
XXH_errorcode      XXH256_update (XXH256_state_t* statePtr, const void* input, size_t length);
void               XXH256_digest (const XXH256_state_t* statePtr, void* out);

/*
These functions calculate the xxHash of an input provided in multiple smaller packets,
as opposed to an input provided as a single block.

XXH state space must first be allocated, using either static or dynamic method provided above.

Start a new hash by initializing state with a seed, using XXHnn_reset().

Then, feed the hash state by calling XXHnn_update() as many times as necessary.
Obviously, input must be valid, meaning allocated and read accessible.
The function returns an error code, with 0 meaning OK, and any other value meaning there is an error.

Finally, you can produce a hash anytime, by using XXHnn_digest().
This function returns the final nn-bits hash.
You can nonetheless continue feeding the hash state with more input,
and therefore get some new hashes, by calling again XXHnn_digest().

When you are done, don't forget to free XXH state space, using typically XXHnn_freeState().
*/

#if defined (__cplusplus)
}
#endif
